| Tiktech Upminster Ltd | Wholesale & retail | 2025 |
| Tiny Team Limited | Information & communication | 2025 |
| Titan Brickwork Limited | Construction | 2010 |
| Titan Roller Shutter Doors Ltd | Manufacturing | 2022 |
| Tj's Decorating Contractors Ltd | Construction | 2024 |
| TJJ Contracts Ltd | Construction | 2025 |
| TK Contracts Limited | Construction | 2019 |
| TLC Carpets Ltd | Construction | 2022 |
| TM Spaces Ltd | Real estate | 2017 |
| TO Your Door Ltd | Transport & logistics | 2025 |
| Toddler Sense Basildon & Billericay Ltd | Education | 2017 |
| TOM Harris Health and Fitness Limited | Arts & recreation | 2019 |
| Tomkyns Estate Limited | Real estate | 2022 |
| Top Medical Ltd | Health & social care | 2021 |
| Top of the Range Limited | Wholesale & retail | 2018 |
| Topo Tax Limited | Information & communication | 2025 |
| Tops London Limited | Information & communication | 2008 |
| Total Build Essex Ltd | Construction | 2022 |
| Total Clean BIO Solutions Ltd | Administrative & support | 2026 |
| Total Sportz Ltd | Arts & recreation | 2016 |
| Total Trading Limited | Wholesale & retail | 2015 |
| Toth, Loftus and Campbell Ltd | Real estate | 2024 |
| Toth, Toth & Sons Limited | Real estate | 2010 |
| Touch of Serenity Limited | Other services | 2014 |
| Tough NUT Productions Limited | Professional & scientific | 2025 |
| Tower M&E Limited | Professional & scientific | 2017 |
| Towrite Direct Limited | Wholesale & retail | 2023 |
| TRA Capital Limited | Administrative & support | 2023 |
| Trade Click Limited | Wholesale & retail | 2017 |
| Traders Automotive Limited | Wholesale & retail | 2020 |
| Train With ABS Ltd | Arts & recreation | 2021 |
| Travdek Ltd | Administrative & support | 2023 |
| TRB Financials Limited | Extraterritorial | 2004 |
| Tredz Plastering Ltd | Construction | 2023 |
| Trendy Nails & Beauty Ltd | Other services | 2012 |
| Trigona Solutions Limited | Information & communication | 2006 |
| Trilex Services Limited | Construction | 2019 |
| Trios AMS Limited | Administrative & support | 1998 |
| Trios Compliance Limited | Other services | 2005 |
| Trios Facilities Limited | Extraterritorial | 2006 |
| Trios Facilities Management Limited | Construction | 1998 |
| Trios Secure Limited | Administrative & support | 1996 |
| Trios Skilz Limited | Other services | 1998 |
| Triosgroup Limited | Other services | 2004 |
| Triple D Property Management Ltd | Real estate | 2025 |
| Triple D Services Limited | Administrative & support | 2021 |
| Tripp 180 Consultancy Limited | Information & communication | 2010 |
| Trojan Group Ltd | Administrative & support | 2016 |
| True North Life Coaching Ltd | Other services | 2024 |
| Trumec Ltd | Construction | 2023 |
| TTC Consultancy Ltd | Real estate | 2026 |
| Tuck & KE Ltd | Construction | 2012 |
| Tudor Cottage Building Ltd | Construction | 2022 |
| Tulina Health and Aesthetics Ltd | Health & social care | 2026 |
| Tulip Media Global Ltd | Professional & scientific | 2024 |
| Tunatime Ltd | Extraterritorial | 2026 |
| Turkman Cars Limited | Wholesale & retail | 2023 |
| Turner Motor Recycling Limited | Wholesale & retail | 2019 |
| Turning Point Counselling Ltd | Other services | 2014 |
| Twelve Project Management Ltd | Professional & scientific | 2023 |
| Twin Pines Consulting Ltd | Information & communication | 2025 |
| Two Squirrels Properties Limited | Real estate | 2019 |
| Twoplusone Studios Ltd | Information & communication | 2024 |
| UCS Procurement Ltd | Wholesale & retail | 2018 |
| UK Bait Company Limited | Agriculture & fishing | 2017 |
| UK Cyber Secure Ltd | Administrative & support | 2016 |
| UK Giant Pro Ltd | Construction | 2024 |
| UK Hub Consultancy Ltd | Professional & scientific | 2024 |
| UK Medical Plus Ltd | Wholesale & retail | 2021 |
| UK Private Finance Ltd | Professional & scientific | 2021 |
| UK USA Connect Ltd | Professional & scientific | 2025 |
| Under the Canvas Ltd | Wholesale & retail | 2018 |
| Unicoupler UK Ltd | Construction | 2015 |
| Uniocean Lines Limited | Transport & logistics | 1993 |
| Unique Furnishings & Interior Design Ltd | Wholesale & retail | 2016 |
| Unique Hope Properties Ltd | Real estate | 2021 |
| Unique Minds Counselling Ltd | Health & social care | 2015 |
| Unisecure Limited | Administrative & support | 2021 |
| Uniserve (Air Freight) Limited | Transport & logistics | 1988 |
| Uniserve (Europe) Limited | Transport & logistics | 1985 |
| Uniserve (U.K.) Limited | Transport & logistics | 1985 |
| Uniserve Drinks Logistics Limited | Transport & logistics | 1976 |
| Uniserve Limited | Transport & logistics | 1984 |
| Unison I.T. Ltd | Information & communication | 2015 |
| Uogp Limited | Transport & logistics | 2006 |
| UP the Road Beauty Limited | Other services | 2024 |
| Upminster Accounting Services Ltd | Information & communication | 2019 |
| Upminster Childminders Limited | Health & social care | 2013 |
| Upminster Containers Limited | Manufacturing | 1968 |
| Upminster Golf Company,Limited(The) | Arts & recreation | 1927 |
| Upminster Hand Car Wash Ltd | Wholesale & retail | 2020 |
| Upminster Hockey Club Limited | Arts & recreation | 2015 |
| Upminster Interiors Ltd | Construction | 2018 |
| Upminster Jewellery Workshop Limited | Wholesale & retail | 2012 |
| Upminster Masonic Hall Limited(The) | Hospitality | 1947 |
| Upminster Nutrition Limited | Health & social care | 2026 |
| Upminster Pathology Services Ltd | Health & social care | 2018 |
| Upminster Pavilion Club Limited | Arts & recreation | 2015 |
| Upminster Periperi Ltd | Hospitality | 2023 |
| Upminster Recovery Limited | Wholesale & retail | 2024 |